Human fathers in many cultures provide a significant amount of child care and play important roles in the cognitive, emotional, and psychosocial development of their children. At the same time, fathers and father surrogates perpetrate a disproportionately large number of instances of severe physical child abuse and child neglect, often in association with high levels of stress or stress-related psychopathology. The factors contributing to child maltreatment by fathers have received surprisingly little attention;however, stress, associated with such factors as unemployment, financial hardship, and parenting difficulties, is thought to play a role. In mammalian mothers, including women, hormonal and neural changes associated with pregnancy, parturition, and lactation lead to reductions in stress-responsiveness, anxiety, and fearfulness, changes that are thought to facilitate the onset of maternal behavior and to buffer maternal care from inhibition by stress or anxiety. It is unknown whether fathers in biparental species undergo similar changes in stress-responsiveness and emotionality. The onset of paternal care in these species, however, is associated with altered activity of several hormone and neuropeptide systems that have been implicated in the regulation of the stress response and emotionality. We suggest, therefore, that these neuroendocrine changes may function to reduce anxiety, fearfulness, and stress-responsiveness in new fathers, thereby facilitating the onset and maintenance of paternal behavior and reducing the likelihood that paternal care will be inhibited under stressful or anxiogenic conditions. In the proposed research, we aim to identify both the effects of stress on paternal care and the effects of fatherhood on stress-responsiveness in a biparental rodent, the California mouse. Specifically, we propose to determine (1) whether paternal care is inhibited by acute and/or chronic stress, and (2) whether fatherhood alters behavioral, hormonal, and neural responses to acute and chronic stressors. These studies will provide unique insights into mammalian paternal care and ultimately may have implications for preventing abuse and neglect of human children by fathers. PUBLIC HEALTH RELEVANCE: Many human fathers make important contributions to the care and development of their children;however, fathers and father surrogates are also responsible for a disproportionately large number of child physical abuse and neglect incidents, often under stressful or anxiogenic conditions. The proposed research will use a biparental rodent, the California mouse, as a model system to investigate how stress affects paternal care and, conversely, whether fatherhood influences males'behavioral, hormonal, and neural responses to stress. This research will substantially advance our understanding of the biology of paternal behavior in humans and other mammals, and may ultimately have implications for the prevention of child maltreatment by fathers.